The Avengers was a guaranteed blockbuster before the first scene was shot, so it would have been easy to play it safe. Thankfully, writer director Joss Whedon doesn't do mediocre: a well-written story with fully realized characters, it bore his quirky sense of humour, was thrilling, dramatic and it connected with audiences on every level and made buckets of cash. So what do you do for the encore? Go bigger of course.

With the forces of Hydra running amok, the Avengers are working overtime. Tired of being tired and getting hurt Tony (Robert Downey Jr.) asks Dr. Banner (Mark Ruffalo) to help with an experiment in Artificial Intelligence. The goal is to create an army of sentient robots that can protect the world, unfortunately things donâ€™t quite go as planned, and they end up spawning Ultron (voiced by James Spader) a super robot who decides that humanity is the only real obstacle to peace. As if things weren't challenging enough, Ultron tricks a pair of pissed off super twins into joining his quest for global genocide.

The are no recaps or reminiscences to lull viewers in to Age of Ultron, instead the movie launches into action the second the lights go down, and what a scene it is: people are yelling, machine guns are rattling, ordinance is exploding, Hulk is smashing, and yet it is as funny as it is action packed. We also get to see how the team dynamic has evolved, and new relationships that will take the story in different directions, an apt summary for the rest of the film.

As the story unfolds, Whedonâ€™s skill as a showrunner (he supposedly ran three shows simultaneously while one is usually too daunting for most) shines through: not only does he manage a sizeable returning cast he also expands their narratives (especially Jeremy Rennerâ€™s Hawkeye). And in a fit of multitasking mastery he then introduces several new characters â€“ Quicksilver (Aaron Taylor-Johnson) and Scarlet Witch (Elizabeth Olsen) among others â€“ and yet no one is shortchanged.

Robert Downey Jr. once again gets many of the choicest lines, but James Spader's Ultron is a definite contender in the charisma contest: not only is he a vicious versatile villain with his booming bass, he also possesses amazing insight and a razor sharp wit, which Spader capitalizes on. Olsen provides an intensity previously lacking in the franchise, fitting given her characterâ€™s pivotal role and I look forward to seeing what theyâ€™ll do with her character in the future.

One of Whedon's central themes in Ultron is responsibility and finding the humanity in everyone, which leads to several emotional and soul searching scenes, which, while effective, do put the brakes on the pacing. Thankfully there are enough outsized action sequences to blow the story back on track; the one involving the Hulkbuster suit (a snippet of which is in the trailer) is worthy of admission alone.

Age of Ultron features Whedonâ€™s trademark off kilter sense of humour, a huge ensemble cast of fully fleshed out characters, superb direction, action sequences that will make Michael Bay jealous, sets up the franchise for future expansion and above all is entertaining as hell. Unless you are opposed to fun, check it out.